Shape selective naphtha processing



July 30, 1968 P. B. WEISZ SHAPE SELECTIVE NAPHTHA PROCESSING 2Sheets-Sheet 2 Filed May 4, 1966 2 R m w W V m 0U M [M @v 9v wm ww mm w29E2mm+mu a QM QN 3 658mm $0 m .8 9 w m w m m m N m E mm; 3 8 s Q N 9 8E20 to 5 20 596mm mm 8 N b \K Age/7f United States Patent 3,395,094 SHAPESELECTIVE NAPHTHA PROCESSING Paul B. Weisz, Media, Del., assignor toMobil Oil Corporation, a corporation of New York Filed May 4, 1966, Ser.No. 547,608 11 Claims. (Cl. 208-62) ABSTRACT OF THE DISCLOSURE Thedisclosure relates to the method of improving the liquid reformateyield-octane number relationship by the particular combination ofselected reforming conditions in combination with shape selectivehydrocracking of normal paratfins remaining in the reformate product.The relationship of operating conditions is particularly concerned withthe disclosure of FIGURE 1 wherein it is shown that the yield-octanerelationship of a reforming process can be significantly improvedproviding that severity of the platinum reforming operation does notexceed a product octane number of about 100 while obtaining furtherdesired improvement in octane number of the reformate product thusformed by the shape selective hydrocracking of the reformate product inthe presence of having activity and selectivity limited to substantiallywithin the pores of the shape selective catalyst by virtue of its methodof preparation.

This invention relates to methods and processes for converting petroleumnaphthas to aromatic rich products including relatively high octanegasoline products. In one aspect, the present invention is directed toone or more methods for selectively conducting chemical reactions withan arrangement of catalytic compositions possessing particular selectiveconversion properties with respect to different hydrocarbon componentsin a naphtha boiling feed. More particularly, the present inventionrelates to effecting the selective catalytic conversion of hydrocarboncomponents comprising ring, normal and iso-paraflin hydrocarboncomponents in a hydrogen rich conversion process maintained underoperating conditions to produce product rich in aromatics, LPG richgaseous material and/or methane rich gaseous material.

The octane number (ON) of gasoline depends on the character and contentof its various hydrocarbon components. Presently practiced processes forobtaining high octane gasolines from naphthas are known to includereforming processes. Of these, the platinum catalytic reforming processis the one most commonly employed. During reforming the gasoline boilingrange components of the naphtha boiling above about C hydrocarbons aresubjected to a plurality of reactions, with isomerization, cyclization,aromatization and hydrogenative cracking as the major resultingtransformations. While these reactions all participate in accomplishinga gain in octane number quality, such reforming operations have alwaysbeen accompanied by a loss of volume or quantity of gasoline boilingrange product. As is well known, progressively greater yield losses mustbe accepted in exchange for improvements in octane quality, as higherprocess severity is employed, that is, the greater the ON (octanenumber) quality target is.

It is an object of this invention to provide an improved method andprocess for upgrading naphtha boiling hydrocarbons.

It is a further object of this invention to provide aromaticconcentrate-s from naphtha boiling hydrocarbon fractions.

It is a still further object of this invention to provide an improvedmethod and process for selectively upgrading the components of paraffinrich naphthas for the production of high volume yield of gasolineproduct of desired high ON quality in combination with gasiform productrich in LPG product material.

It is a still further object of this invention to selectively upgradeparaffin rich naphthas to an aromatic rich product and gasiform materialrich in methane.

Other objects and advantages of this invention will become more apparentfrom the discussion hereinafter presented.

In accordance with this invention, one or more of the above objectivesis accomplished by establishing specific catalytic reaction methods andsystems arranged to provide a particularly selective and desirablecombination of chemical transformations to occur. The newly selectiveupgrading operation of this invention hereinafter described willtherefore, and for convenience, be termed a selectoforming operation.

The selectoforming operation of this invention comprises contacting anaphtha boiling range starting material with at least two distinctlydifferent catalyst compositions, comprising a platinum type reformingcatalyst on the one hand, employed in cooperation with an n-paraffinselective conversion catalyst differing substantially from the platinumtype reforming catalyst in chemical composition, structure and purpose.The selective conversion catalyst employed herein is characterized inone aspect by a highly selective ability to convert normal paraffinhydrocarbons in admixture with other hydrocarbons to lower molecularweight saturated gasiform product materials when operating under theselectoforming operating conditions herein described as regards thepresence of hydrogen, operating pressure, temperature, vapor residencetime, and catalyst residence time. Furthermore, the selective conversioncatalyst and operating conditions under which employed providesconversion of normal paratlins to saturated products substantiallywithout the production of olefinic products, whereby continued,regeneration-free operation is possible for the processing of from about300 to about 3000 or more volumes of naphtha per volume of catalyst.Therefore, the present invention provides on the one hand a gasolineupgrading process wherein the plurality of reactions occurring tocomponents in the naphtha feed are selectively altered in a direction sothat reactions resulting in loss of liquid product are now shifted tomore selectively involve the lower ON components. Thus, desired targetON are attainable with even a higher than usual desired product yield.On the other hand, the upgrading process of this invention permits thepreparation of aromatic concentrates and saturated gasiform productsunder conditions allowing longterm on-stream time in, for example, afixed bed operation.

In the selectoforming operations contemplated by this invention anaphtha charge material boiling in the range of from about C andpreferably from about C up to about 380 F. or higher is passed withhydrogen at least initially in contact with a platinum type reformingcatalyst A and then in contact with the selective conversion catalyst.Generally, contact with the catalyst types of this invention is arrangedto occur substantially sequentially in a suitable reactor system.However, provisions are also contemplated for effecting an initialseparation of the reformate efiluent to recover lower boilingconstituents therefrom before subjecting the remaining higher boilingreformate effluent in the presence of hydro-gen to contact with theselective upgrading catalyst.

Platinum type reforming catalyst referred to herein as catalyst A forconvenience may be selected from a number of the known reformingcatalysts of the prior art. They may include, for example, alumina inthe eta, chi or gamma form and mixtures thereof in combination with anoble metal. Platinum type includes, for example, the

metal series which includes platinum, palladium, osmium, iridium,ruthenium or rhodium and mixtures thereof deposited on a suitablesupport. Generally, the major portion of the catalyst will be aluminaand may comprise as much as about 95% by weight or more of the catalyst.Other components may be combined with the alumina carrier, such as theoxides of silica, magnesium, zirconium, thorium, vanadium, titanium,boron or mixtures thereof. The platinum-alumina combination, either withor without one or more of the above-listed components such as silica,etc., may also be promoted with small amounts of halogen such aschlorine and fluorine, in amounts ranging from about 0.1% up to about 5by weight. Generally, less than about 3% of halogen is employed with theplatinum type catalyst. In a preferred embodiment, the reformingcatalyst carrier material is a relatively high surface area material,preferably on eta alumina material of at least about 100 square metersper gram. Preparation of the type A catalyst may be accomplished by manydifferent procedures described in the prior art. In one procedure analumina carrier material is impregnated with the acid or salt of one ormore of the herein-described platinum type hydrogenating component inamounts that range from a fraction of a percent up to about 1% by Weightbut generally not substantially more than about 0.6% by weight ofplatinum is employed.

It is to be understood that a naturally occurring or syntheticallyprepared alumina with or without silica may be employed as a carriermaterial or support for the platinum type reforming catalyst.Preferably, the platinum-alumina catalyst employed comprises a highsurface area material such as an eta base alumina discussed above.Before use, the high surface area platinum catalyst may be reduced in ahydrogen atmosphere and maintained preferably in a relatively drymoisture-free atmosphere before being put on-stream. Desiccatedconditions for the catalyst are preferred since it has been found that agiven moisture and certain related temperature level that a relationshipexists which decreases the desired high surface area of the catalyst andhas a simultaneous deactivating effect on the catalyst. Accordingly, itis preferred to employ in the platinum reforming steps of thisinvention, relatively dry reforming conditions. This is particularlytrue, however, when employing relatively low pressure reformingconditions below about 400 p.s.i.g. and not substantailly above about200 p.s.i.g.

It is to be understood that the term platinum type reforming catalyst ortype B catalyst designates a catalyst which performs the well-knownreforming reactions of hydroisomerization and aromatization underconditions creating a negligible concentration of olefins in theefiiuent product. While the above described catalysts are examples ofthis class, the platinum type catalyst and term as used in connectionwith this invention should not be construed to be restricted to aparticular chemical composition per se, as regards the platinum typemetal nor the base or support material.

For example, it is contemplated using as a platinum type reformingcatalyst, compositions which may include a crystalline aluminosilicatebase substance having a pore structure sufiiciently large to allowpassage therein of substantially all molecules contained in a naphthacharge, and associated with a dehydrogenative element of the transitionmetal series, and having its acidic catalytic activity adjusted to arelatively low level which is characterized by an alpha value of lessthan 1.0 and preferably of about .01 to 0.1. The alpha scale andmeasurement has been described in publication in the Journal ofCatalysis, vol, 4, No. 4, August 1965, pages 527 to 529. In the case ofcatalysts with associated dehydrogenative metal, the alpha test iscarried out after suitable poisoning of the metal activity as peradvance contact with a sufiiciently large amount of hydrogen sulfide. Inthe above example, the prescribed low level of acidic activity may beachieved by providing a controlled and relatively high concentration ofalkali metal ion concentration within the aluminosilicate.

The selective conversion catalyst herein referred to as type B catalystis a porous solid particle material having a majority of its pores ofsubstantially uniform small dimension, large enough to allow uptake andegress of normal paraflin molecules, such as, for example, n-hexane, buttoo small to allow a similar uptake of either branched chain or cyclichydrocarbons, such as, for example, methylpentane, cyclohexane orbenzene. Accordingly, the selective catalytic material, type B is ahighly porous material wherein a substantial majority of its pores areof a uniform dimension in the neighborhood of about 4.5 to about 6.0Angstrom units effective diameter. Type B catalyst is essentially aselective hydrocracking catalyst substantially provided with in-poreacid activity cracking sites and in-pore catalytically effectivehydrogenation-dehydrogenation sites. In some cases, one of the twofunctions or types of catalytic sites may be associated with themolecular shape selective material but externally located. Thehydrogenation-dehydrogenation component introduced during manufacture ofthe catalyst, involves one or more of the elements known as thetransition metals. Preferably, one or more of the elements of nickel,cobalt, molybdenum, iron, or of the platinum or palladium family areemployed. One or more of the elements employed may also involve anelement of the higher molecular weight transition series which havehydrogenation-dehydrogenation activity, such as tungsten.

In one embodiment, the catalytically active solid material comprisingtype B catalyst is a modified zeolitic oxide, having a crystalline,rigid and uniform cavity structure of the aforementioned dimensions.Examples are to be found among a number of aluminosilicate minerals, andamong synthetically prepared crystalline aluminosilicates which havestructures analogous to, and sometimes differing from minerals known tooccur naturally: chabazite, gmelinite, stilbite, erionite, oifretite,epistilbite, desmin, zeolites S, T, A, ZK4, ZK-S and others. It is to benoted that the terms erionite and ofifretite will be considered to beidentical in meaning as regards reference to the same or closelyequivalent structure mineral form, in accordance with the findingsreported in Mineralogical Magazine, vol. 33, pp. 66-67, 1962, by M. H.Hey and E. E. Fejer entitled The Identity of Erionite and Olfretite.

Other porous materials may be employed provided they possess the abovedescribed characteristic pore dimensions. Thus, for example, porouscarbons can be employed which have undergone suitable treatment toconvey to them pore dimensions in the desired range of from about 4.5 toabout 6.0 Angstroms.

These solids of desired porosity are modified to produce useful catalystby introduction of one or more of the above described transitionelements in such a way that a majority of the final quantity of suchelement is located in the internal porous structure, in contrast tosurface deposition on the circumferential surfaces of the individualsolid grains or particles.

Introduction of one or more of the metallic catalytic component may beachieved either by processes allowing this component to penetrate theexisting or preformed porous solid and be fixed therein, or by formationon synthesis of the porous solid itself in a compositional environmentwhich contains the desired metallic component in suitable form so as tobe incorporated in the porous structure in the formation of the poroussolid or in the course of its modification to be desired pore structure.

In another aspect of this invention, molecular sieve like carbons can beused to advantage which. are produced by heat treating to pyrolitictemperatures, high polymer materials such as polyvinylchloride,polyvinylidine chloride, polystyrenes, polystyrenes containing halo-,sulfonate or other groups on the aromatic nuclei, polymers frommonomeric units containing elements or groups comprising elements fromGroups VI and VII of the Periodic Table.

Thus, for example, suitable porous carbons can be produced from Saranpolymer at high temperatures. Methods have been described by Dacey andThomas in the Transactions of the Faraday Society, vol. 50, 1954,beginning with p. 740; and by Lamond, Metcalfe and Walker, in Carbon,vol. 3, 1965, beginning with p. 59. Other organic polymers may alsoserve as starting materials such as coals, anthracite and othercarbonaceous solids that can be converted to suitable porous solidssimilar to the base material used for the B type catalyst hereindescribed.

It is further contemplated that specific qualities in the design andcontribution of the B type catalyst component in cooperation withspecifically chosen process conditions are particularly preferred toimpart unusual economies and stability of performance to theselectoforming process. Thus, the acidity of the type B catalyst solidor solid composite, if any, in the type B reaction zone will preferablybe maintained within desired limits, and these limits will bear acorrelation to the temperature of operation employed therein.

Accordingly, it is preferred to impart the type B catalyst with certainmagnitudes of acid catalytic activity. For example, when LPG product ispreferred over methane, the preferred acid activity Will have an alphavalue in excess of 10. If the selectoforming process employs thecatalyst at a temperature of 900 F. or higher, a more preferred aciditylevel is between and 300 alpha; for operation more nearly at 800 F.,above about 500 alpha; for operation near 700 F., above about 2000alpha. A very practical method of assaying the alpha acidity of the typeB catalyst is that of testing its n-hexane cracking activity underconditions of cracking, in the absence of hydrogen. Such a procedure infact constitutes the procedure of the alpha test, as outlined in apreviously cited publication.

In order to acheve the required activity level without exceeding thepreferred range, for purposes of operating stability, the followingtypes of catalysts or procedures for making same, constitute preferredexamples:

Suitable crystalline aluminosilicates, such as desmine, ZKS, describedin US. Patent 3,140,251, erionite, chabazite, and others, may beprepared having an appreciable fraction of cation sites occupied byhydrogenor hydrogen precursor cationic form such as ammonium, prior toany calcinationan appreciable fraction by transition metal ions, and thebalance by one or more of the alkaline metals or alkaline earth metals.

For example, erionite may be acid treated to remove initial cations andimpurities, and subsequently base-exchanged with a solution of Ca-ion,or Mg-ion, or mixture therefore until most of the cation exchangecapacity is satisfied by that ion. The transition metal ion may beintroduced simultaneously, or by a subsequent exchange process. A moreexacting control of the catalyst quality may be achieved by exchange ofthe zeolite simultaneously with a solution comprising at least one ofthe ions of each of the tWo groups comprising in the first group Mg, CaSr and in the second group H+ and NH in such proportion as to result inan ultimate product of desired acidity. In every case, the transitionmetal may also be introduced as described above, that is before,simultaneous with, or after the aforesaid exchange. Extended calcinationis indicated for increasing the acidity of NH containing preparations.

It is also possible to control the acidity of catalyst type B prior touse in a selectoforming operation, or in situ, if overactivity is to bereduced, by contacting limited amounts of ammonia or ammonia producingvolatile components with the type B catalyst charge.

In accordance with the invention herein described a naphthaboiling-range charge material is passed over at least two separate anddistinct solid catalyst compositions A and B, described above, in thepresence of hydrogen, under temperature, pressure and feed-rateconditions characteristic of a p1atinum-type reforming operation. It iscontemplated employing catalysts A and B in one or more separatecatalyst beds located in one of a sequence of separate reactors whereinthe order of catalyst loadings are such that the reactant streaminitially contacts solid catalyst particles of predominantly type Acatalyst prior to contact with solid particles of predominantly type Bcatalyst. Intermingled mixtures of particles of catalyst A and B may beemployed in part of one, two, or more beds in the system. However,contact with type A solid shall again predominate during the early orinitial contact portion of the sequence. With this feature in mind, theconcentration of catalyst B in any one bed may amount to an abruptchange or be arranged to increase gradually and in increments within agiven reactor or catalyst bed in the direction of reactant flow.

In any of the above arrangements employing separate or an intermingledmixture of identified catalysts A and B, the conversion eltectedgenerally will be in a direction tending to favor aromatization ofcyclic compounds and elimination of paraflin compounds from the naphthafeed. With proper conditions of severity, and a more specific choice .ofcatalyst distribution within the broad characteristics described above,the reaction mechanisms effected in the presence of catalysts A and Bmay be controlled and directed either to serve specifically as a processproducing primarily an aromatic rich concentrate, or conditions andcatalyst distribution may be optimized to create a process producing amotor gasoline of desired high target octane number with relatively highproduct yield.

When a highly aromatic product is desired, a naphtha feed materialboiling in the range of from about a C up to about a C hydrocarbonfraction may be chosen as a feed or separate or combined portionsthereof may be employed, for the production of benzene, toluene andxylene rich product material. The distribution of catalysts A and B willbe chosen such as to include portions of intermingled components A and Bin a downstream portion of hydrocarbon contact. For this purpose ofproducing an aromatic concentrate, elimination of a major portion of alltypes .of paraifins, that is, both normal and isoparaffins, iscontemplated and the presence of intermingled catalysts A and B in thesequence has been found to be important. Accordingly, an example of thedistribution of catalyst types within a process arrangement using asingle reactor comprises employing at the inlet end of the reactorcatalyst particles of type A constituting of the fill, While toward theoutlet end of the reactor the relative concentration of catalyst B risesup to about 75%. On the other hand, using a tworeactor arrangement, theone first contacted contains only catalyst A, while the seconddownstream reactor contains both A and B in intermingled admixture ofabout 50% of each catalyst. It is evident from the above that manyvariations of catalyst arrangement are possible which incorporate theprincipal features above described.

When it is desired to produce a motor gasoline product of high targetoctane number, such as for example, 102 ON (Research, 3 ml. TEL), withunusually good product yield, the distribution .of catalysts A and B isso chosen as to include a substantially abrupt change of catalyst type Ato catalyst type B in the downstream direction of hydrocarbon flow sothat substantially no volume exists in which there is any substantialmixing of both catalysts A and B. That is, one example of a suitablecatalyst arrangement comprises providing contact with catalyst A in onebed of catalyst followed by contact with type B catalyst in a secondportion of catalyst bed within a single reactor. On the other hand,catalysts A and B may be retained in separate catalyst beds in separatereactors so that the reaction product separated from catalysts A willthen contact catalyst B in a separate reactor. Furthermore, a bed ofcatalyst B may occupy only a portion of a downstream reatcor of amulti-vessel sequence. These arrangements of catalyst beds all have thecommon feature, however, that substantial preliminary contact is firstachieved over the highest concentration of type A catalyst, before anysubstantial contact of the charge stream is provided with aconcentration of type B catalyst.

Therefore, when an optimum yield-octane number relationship isspecifically desired in the production of a high target ON motorgasoline by the selectoforming upgrading process herein described, thecatalyst compositions employed are generally arranged to provide thehighest concentration of catalyst B type in at least the last reatcor,bed of catalyst, or last portion of same, when viewed in the downstreamdirection in which the naphtha feed passes over the total catalystcontact mass.

It is to be understood, of course, that the salient features of thisinvention are not defeated by the use of other contact operations whichmay be applied subsequent to the above conversion operation. The use ofthe highest concentration of B type catalyst at the end of the contacttrain is to be interpreted to mean that no further appreciableisomerization conversion zone follows the contact with the highconcentration of B type catalyst. That is, isomerization inducingcatalyst, such as ordinary reforming type catalysts need not be used tocreate deliberate and substantial further conversion following theselectoforming operation. It is permissible, however, to provide furthercontact or conversion opportunities, if so desired, over solid contactmasses which do not otter both an acidic and ahydrogenation-dehydrogenation component in intimate association, and inthe absence of molecular shape or size restrictive properties whichwould in fact and otherwise characterize such material as a type Bcatalyst. For example, contact with silica-alumina, a solid sorbent, amolecular sieve devoid of internally active dehydrogenative components,a non-selective hydrogenation catalyst, and with other solids may bepracticed subsequent to the selectoforming operation without interferingwith the principles of the invention. Thus, it is contemplated that thelast catalyst bed or portion thereof may contain catalyst type B andalso a platinum type component located externally of the intraporousspace as previously discussed with respect to catalyst B, but devoid ofacid propertes which when located externally would provide basis forisomerization type conversion. On the other hand, it is contemplatedproviding a contact zone containing silica-alumina, or acid zeolite,devoid of hydrogenation dehydrogenation active metals, downstream of orin admixture with catalyst component B. In particular, a combination oradmixture of catalyst B with another acidic solid particle material iscontemplated to provide specific characteristics aiding in the promotionof desirable selective conversion of normal parafiins. Examples for suchadded acidic solids are silica-alumina, silica-zirconia,silica-magnesia, zirconia-alumina, halogen containing alumina, hydrogenand multivalent acidic metal forms devoid of hydrogenation activity suchas rare-earth and alkaline earth metal forms of aluminosilicate zeoliteslike faujasites, mordenites, clinoptilolites, zeolites X, Y, L andothers. Such combination of a poresize selective catalyst containing ahydrogenative metal as previously discussed as characteristic ofcatalyst B in combination with an acidic solid catalytic material shouldalso be considered to fall within the scope of the definition of type Bcatalyst of this invention.

The present invention provides an improved and novel method of upgradinga naphtha boiling material to a desired high target ON product in highproduct yield. The method of this invention encompasses the steps ofcontacting a naphtha feed with a reforming catalyst under relativelyrestricted reforming conditions selected to limit the reactionconversion severity to substantially an intermediate high octane numberor aromatic concentrate product of relatively high yield having anoctane number substantially below the desired :product target ON andthereafter contacting the intermediate product material withpredominantly type B catalyst to affect further selective conversion toa final aromatic rich product comprising a gasoline boiling rangeproduct of desired higher target octane number.

In reforming operations it is known that as severity is increased toachieve higher and higher octane numbers (ON) product, the ON increaseis obtained primarily by paratfin isomerization, naphthene aromatizationand five carbon ring naphthene aromatization. At relatively highseverity conditions, paraflin-to-aromatics dehydrocyclization becomesimportant and is also accompanied by progressive elimination ofremaining paraffins to gaseous products, thus increasing ON at theexpense of substantial liquid volume losses. However, by controlling thereforming reaction mechanisms in the manner of this invention, theselectoforming operation, selectively directs the conversion andelimination of the lowest ON compounds in the hydrocarbon fluid, namelyits n-parafiin constituents. Accordingly, the selectoforming method andprocess herein described provides significant and unusual benefitsspecifically at upgrading levels where high octane numbers are to beachieved. Accordingly, the selectoforming operation herein described. isdistinguishable from and substantially diametrically opposed to theprior art method of operation which operates through indiscriminate anduncontrolled removal of all types of paraflins from the naphtha feed tobe upgraded to high ON levels. In a more particular aspect, theselectoforming operation herein described permits an unusual advantagein product yields when applied to producing gasoline target octanenumbers of at least about 98 and preferably at least about 100 ON, andeven more particularly for target ON of about 102 or higher (in terms ofresearch ON, with 3 cc. TEL).

The methods of operation and processes herein provided are of a scopethat includes in one embodiment the simultaneous production of high ONgasoline product in unusually high liquid yields and of LPG fuelproducts. However, the selectoforming operation may also be adjusted toproduce either aromatic concentrates or high yield of high octane numbergasoline as liquid product together with either LPG or with a methanerich gaseous product such as is useful for consumer gas or city gas. Inthe LPG rich gas producing operations, a catalyst composition of the Btype is employed which contains the hydrogenation dehydrogenation metalcomponent preferably in a non-aggregated, highly mono dispersed form, inprocessing steps that permit continuous separation and withdrawal offormed LPG gaseous product from the process. Accordingly, the type Bcatalyst preferred in this type of operation should contain the metalcomponent in a highly dispersed form. It is also preferred, to use amono-dispersed form of the transition metal element, placed into theinterior of the solid of special uniform pore structure, such as adispersion at the mono-atomic or mono-ionic level which does not give asubstantial X-ray diffraction response corresponding to the bulk metalform of the transition element employed. For example, a suitablemono-dispersed form of N-chabazite catalyst will not give X-raydiffraction lines corresponding to Ni metal per se. Re-exchangeabilityof the mono-dispersed metal with another ion, such as calcium forexample, in the aqueous phase is often characteristic of this state ofthe catalyst. Accordingly, this mono-atomic catalyst composition form istherefore in direct contrast to the prior art teaching of metal loadedcatalysts where the elements are said to be reduced to the metallic formand X-ray diffraction patterns of the metallic state per se can beobtained.

On the other hand, when it is preferred to produce methane rich gas inpreference to LPG product material, the method of operation ispreferably characterized by the use of a type B catalyst compositioncontaining the hydrogenation-dehydrogenation metal component in anaggregated form, internal to the pore system of molecular dimension,together with processing steps that permit the continuous separation andwithdrawal of methane rich gaseous material produced in the process. Inthis latter method of operation, the catalyst B composition preferablycontains one or more metals such as Ni, Pt, Pd or other suitablehydrogenative-dehydrogenative metal component within the uniform porestructure, in a state of metallic aggregation. This catalyst compositionmay be obtained by various procedures which include introducing a highconcentration of metal, such as corresponds to about 30% or more of itsion-exchange capacity; by the introduction of metal as non-ionic speciessuch as by gaseous decomposition of a carbonyl or by heat treating thecatalyst containing relatively dispersed metal at sufficiently hightemperatures in the presence or absence of steam, oxygen, hydrogen,etc., so as to cause substantial migration and aggregation of elementalunits of the transition element used.

The operating conditions employed in the process embodiments of thisinvention are selected such that a catalyst of type A will be exposed torelatively typical reforming operating conditions including temperaturesin the range of from about 800 F. to about 1000 F., preferably fromabout 890 up to about 980 F., liquid hourly space-velocity in the rangeof from about 0.1 to about 10, preferably from about 0.5 to about apressure in the range of from about atmospheric up to about 700 p.s.i.g.and higher, preferably from about 100 to about 600 p.s.i.g.; and ahydrogen-hydrocarbon ratio in the range of from about 0.5 to about 20and preferably from about 1 to about 10.

On the other hand, the catalyst of type B category generally may beemployed at operating conditions similar to and within theabove-identified operating conditions of a reforming reaction, or insome embodiments at lower temperature and similar or higher pressureconditions. However, one of the important aspects and embodiments of theinvention relates to contacting the hydrocarbon reactant stream withboth types of catalysts under similar operating conditions. Therefore,it is possible to have embodiments in which the two diiferent types ofcatalysts are contained in successive beds in one or more reactors inthe process stream. Such circumstances provide engineering advantagessuch .as adiabatic operation, avoidance of heaters or coolers betweenstages of the process, minimum need for interstage compressor orexpansion facilities, etc. However, it is also within the scope in someembodiments of this invention to expose type B catalyst to asubstantially wider range of operating conditions than is characteristicof a typical reforming operation. Therefore, catalyst type B canencounter temperatures in the range of from about 500 to about 1000 F.,or higher; pressures from about atmospheric up to as high as about 5000p.s.i.g.; LHSV in the range of from about 0.1 to about 40 and a hydrogento hydrocarbon ratio in the range of from about 0.1 to about 40.

The selective conversion relied upon in the contact step involving thecatalyst of type B, was found to proceed under conditions of pressureand temperature which are regarded as either hydrogenative oraromatizing in the thermodynamic sense. Therefore, the operation may beeffected at lower temperatures and higher pressure than is generallyallowable in the normal reforming operation which is limited to therange of aromatizing conditions, that is for an equilibrium which favorsaromatics in the reversible system, naphthenes aromatics. In addition,the temperature of operation applicable to contact with type B catalystwill depend on and be correlated to the acidity of the B catalystcomposition. That is, if it is prepared to contain much acidityinternally, or is admixed with external acidic solid, operation at arelatively lower temperature can be achieved.

In any of the arrangements above discussed using crystallinealuminosilicate or zeolite support material for the type B catalyst, itis particularly preferred to have a zeolite composition with a silica/aluminum ratio not less 10 than about 2.0 and preferably the ratioshould be at least about 3.0.

It should be noted also that the invention involves a cooperativehydrogen economy between the different parts of the conversion processin that hydrogen consumed by the mechanisms operative on catalyst B isproduced in and derived from the conversion events over catalyst A.

Shape selective conversion catalysts type B suitable for use in themethod of this invention were prepared as follows:

Catalyst B was prepared from a naturally occurring zeolite (erionite) ofabout 4 to 6 Angstrom pore size. One part by weight of the crystallinealumino-silicate or zeolite was base-exchanged for about 2 hours at roomtemperature with about ten (10) parts by weight of 5% NH Cl solution.This treatment was repeated three additional times for a total time ofthe order of about 20 hours with the last treatment being for about 16hours duration. The residue obtained from this NI-I Cl treatment orbaseexchange step was thereafter water washed to remove chloride fromthe residue and then filtered. The filter cake thus obtained wasrefluxed with about 25 parts (wt.) of 0.5 N nickel acetate solution forabout 10 minutes and then filtered. The filtered solids or residue wasthen again water washed. The residue thus obtained was dried, pelleted,crushed to about 30/60 mesh size particles and then air calcined at atemperature of about 1000 F. for about 16 hours. A sufiicient quantityof the calcined catalyst was placed in a reactor and H reduced oraotivated for about 4 hours at a temperature of about 950 F. and apressure of about 400 p.s.i.g. while maintaining fresh flow of H richgas at about 6 s.c.f./h.

Catalyst B was prepared by following the procedure for the preparationof catalyst B but the final nickel content of the catalyst was. limitedto approximately /2 of that in catalyst B Catalyst B was prepared anddried in the manner identical with that employed to prepare catalyst BHowever, the dried catalyst was subsequently partially chelated bycontacting with an EDTA (ethylene-diamine-tetraacetic acid) to eliminatethe surface (macropore) dual functional non-selective properties ofcatalyst B Analytical data obtained from the catalyst thus treated haveshown that the net effect of the chelating treatment is to reduce thenickel content from about 2.5% (of catalyst B to about 2.0% withoutsignificantaly effecting the alumina content (15.9% for catalyst D;16.5% for catalyst B A more detailed procedure of preparation of thestrictly shape-selective catalyst B, with pores of 4 to about 5Angstroms in diameter is described below.

A naturally occurring zeolite (erionite) was ground to 0.024 inchaverage particle size. The ground or particulated zeolite wascontinuously base-exchanged for a period of about 6 days with about 5%ammonium chloride solution maintained at a temperature of about 180 F.,at a rate of about pounds of ammonium chloride solution per 1.0 lb. ofthe zeolite particles. The resulting NHp -zeolite was water-washed untilfree of chloride ions and subsequently air-dried at a temperature ofabout 230 F. The dried NH -zeolite was reflux contacted for 10 minuteswith 0.5 normal nickel acetate solution, using about 853 cc. of thesolution per 100 g. of the ammonium-zeolite. The resulting slurry wasfiltered and the filter-cake was water-washed, using two one-literwashes to remove excess nickel-acetate. The washed wet cake wasair-dried at a temperature of 230 F. The resulting dried NiNH -zeolitewas treated for 10 minutes at a temperature of about 180 F., with about820 g. of chelating solution per 100 g., of the dried NiNH -zeolite. Thechelating solution was prepared by adding 11.11 g. of EDTA to 1111 ml.of water and by addition of NH OH to adjust to 6.2 the final pH value ofthe solution. The resulting chelated Ni-NIh-zeolite was air-dried at atemperature of about 230 F., and subsequently air-calcined for about 10hours at a temperature of 1050 F. The final product, catalyst 13,, was achelated Ni-H- zeolite.

The chelated and calcined catalyst B prepared as abovedescribed asreduced to about /s particle size and 40 cc. of this material wascharged to a bench-scale isothermal reactor. The catalyst in the reactorwas N purged and H activated, or treated, with H -rich gas at theconditions described hereinbefore with respect to the preparation ofcatalyst B Catalyst B comprising a nickel offretite catalyst wasprepared as follows:

One part by weight of offretite was exchanged for two hours at roomtemperature with parts of 5 normal ammonium chloride and then filtered.This step was repeated three times and the last time the exchange wasmade overnight for approximately 16 hours. A filter cake was obtainedand water-washed and added to parts of refluxing 0.5 N nickel acetate.After ten minutes the material was filtered and again water-washed. Thiscatalyst after drying had the following compositional analysis as shownin examples 11 to 16. A portion of the dried catalyst was pelleted,crushed to /60 mesh and calcined at 1000 F. in an oven for about sixhours.

FIGURE 1 presented herewith and discussed in example 17 presents theyield-octane relationship obtained by the selectoforming process ascompared with that obtained by a normal reforming operation.

FIGURE 2 presented herewith in diagrammatic form shows an arrangement ofprocessing steps for reforming a naphtha charge and selectivelyupgrading the reformate product thus obtained.

Examples 1 to 4 Mixtures of a low and a high octane number paraffinhydrocarbon were contacted with various metal zeolite catalysts of thisinvention to demonstrate enrichment of the high octane component in thecontact stream. Two different charge-stocks employed were:

Percent RON (clear) A {n-Oetane 50 21. 7 iso-Octane..- 50 100. 0 B{n-Hexane 50 24. 8 2methyl pentane. 50 73. 8

The naphtha test charge was injected as a vapor pulse with hydrogen overthe catalyst, a H /hydrocarbon mole ratio of 37/1, and a LHSV (duringhydrocarbon feed) of about 1, at atmospheric pressure, at 900 F. forexamples 1 and 2, and at 700 F., in Examples 3 and 4.

High conversion to eliminate the low octane number component, andenrichment thereby of the high octane number component was observed, asfollows.

Elimination Percent of Original Charge Example Run# Catalyst ChargeStock A Charge Stock B n-C iso-Cs N-C iso-C 1 N1 Ni-Ofiretite. 68 0 l5 0(4.6% Ni) 2 '4 Ni-Ofiretite.. 58 0 24 0 (.4% N1). 3 A Ni-ZeoliteA. 77 62(0.6% Ni). 4 F Ni-Chabazite 42 0 12 Examples 5 to 8 A naphtha boilingrange hydrocarbon mixture of 100.1 ON (R-E-3) was contacted with a 4.6%wt. Ni-oifretite catalyst at various conditions of temperature andpressure within the reforming range. Conditions and results aresummarized below:

Charge naphtha composition, percent (vol.):

2,2 dimethylbutane 10.5 2,3 dimethylbutane 6.2 Z-methylpentane 15.3n-Hexene t 5.8 Benzene 40.8 n-Hexane 21.4

Example N0 5 6 7 8 Pressure, p.s.i.g 400 400 200 200 Temperature, F 800950 800 950 Vol. percent CM product. 66.6 61. 9 77. 3 67.3 n-Crconverted, mole percent of initial 01. 5 86.0 73. 5 82.0 iso-Caconverted, mole percent of initial..." 5. 2 16. 1 6.0 29.0 ON (R-l-3) of05+ product 107.8 107. 5 106.4 109.

N orn.-All runs at 4 LHSV 4 Hg/IIC ratio.

The results of the four examples demonstrate the ON improvementaccomplished by the highly preferential conversion of the normalhydrocarbon in contrast to isoparaffin.

Examples 9-10 A C reformate eflluent stream was simulated by the blendlisted in column 1 of the table below:

The blend has the composition of a reformate, i.e., of a naphthafraction which has already contacted a Pt-catalyst in a reforming zone.It is essentially a mixture of only aromatic and paraffinic components.This material was then contacted with Ni-offretite catalyst B at 2000p.s.i.g., 30/1 molar H /hydrocarbon ratio, at 14 LHSV, at 800 F. Thecomposition of the C fraction efiluent was found to have the compositionshown in column 2 of the above table.

It is to he noted that the low ON component has been greatly reduced inconcentration while the concentration of none of the high octanecomponents have substantially dropped.

The above contact was also repeated at a temperature of about 750 F.This Example 10, produced the product composition shown in column 3.

It is clear from the data of columns 2 and 3 that the average octanevalue of the C products was raised in both cases. The octane numbers,calculated by standard methods, for the compositions of columns 1, 2 and3 are 102.4, 106.4 and 105.3, respectively. In ordinary reforming typeprocessing, isoparaffins are eliminated at least as easily asn-parafiins and, therefore, for the same loss of total paraflin volume,the octane number gain would be smaller. It is noteworthy that noaromatics were lost in spite of the fact that the conditions ofcatalytic conversion, in the presence of a hydrogenation-dehydrogenationmetal component would normally favor such hydrogenation, at theconditions of operation.

These data show beyond any reasonable doubt that the downstreamconversion of a partially reformed naphtha can also be accomplished attemperature-pressure conditions which lie outside of the thermodynamicrange of aromatization conditions. That is, temperatures for this partof the overall naphtha conversion may be lower and pressures may behigher than those typical of reforming conditions per se.

13 It follows from these and the previous examples that this portion ofthe process step may be carried out under operating conditions broadlywithin those of reforming, but also outside of that range of conditions.

Examples 11-16 A nickel otfretite catalyst used in the present study wasprepared and had the following compositional analysis (when analyses areexpressed in terms of equivalent oxides composition):

A portion of the dried catalyst was pelleted, crushed to 30/60 meshparticle size and calcined at 1000" F., in an oven overnight (about 6hours). Two and one half cc. (1.1 g.) were charged to a 10 cc.cylindrical pressure reactor, and activated with hydrogen at 900 F.,atmospheric pressure for one hour. At the end of each run, the catalystwas purged with the same flow rate of hydrogen for 1-2 hours, while thereactor was cooled to 500 F., and left blocked at 2000 p.s.i. overnight.

A 1/1 weight blend of n-octane/2,2,4-trimethyl pentane, 30/1 ml. ratio H/hydrocarbons, was charged over the catalyst at 2000 p.s.i.g., 750-800F., 2-14 LHSV, with the following results:

Example No 11 12 13 14 15 16 Run No 1 1 2 3 4 6 Time, H rs 1 1 1 2 MConversion, w

Ove 1 55. 5 45. 9 15. 2

iso-Octane 11.0 5.3 Nil Material Balance 97.9 99.1

The liquid products in the first three runs contained only iso-octane.The last two runs for which complete material balances were made showedmajor products to be propane, butanes and some pentanes-the butanes were93% normal, and the pentanes 83% normal. Catalytic shape selectivity isclearly demonstrated by the above results. The selective conversion to ahigher octane number product is clearly shown.

Example 17 A C -360 F. Mid-Continent naphtha was processed by initiallycontacting the same with a platinum alumina reforming catalyst underreforming conditions of 500 p.s.i.g. pressure at a reforming severityadjusted to give a 99 ON (R+3) intermediate product composition for theC portion. With the portion of material lighter than C removed, thenaphtha was then further contacted with a 2.5% Ni-offretite catalyst;this contact was carried out at 500 p.s.i.g., a H /HC ratio of about :1and a series of inlet temperature se'verities from 900 F. to 940 F. Theliquid volume yields final product from the successive contacting wasdetermined, as well as the (R+3) ON of that product. The resultingyield-octane relationship was compared with the yield-octanerelationship obtained by conventional 500 p.s.i.g. pressure reforming ofthe same Mid-Continent naphtha over a platinum reforming catalyst alone.The comparison is shown in FIGURE 1 attached.

The C product yield obtained by sele-ctoforming, the new process (markedprocess), and the C product yield from conventional reforming (markedstd. reforming) are shown as curves A in FIGURE 1. They demonstrate theability of the new process to give higher volume yields for a giventarget ON to be achieved. The curves also show that this process isspecifically applicable to a range of high target octane numbers, namelythose near and above a level of about ON (R+3).

When the portion lighter than C is blended back into the' product, theoverall yield comparison, now for C product yield is shown in curves B.The advantage of the new process remains evident.

Examples 18-19 A C hydrocarbon blend simulating a Kuwait 0 -250" F.naphtha, and having an octane number (R+3) of 83.3 was contactedsequentially at 200 p.s.i.g., 950 F., 6.0 H /hydrocarbon, 1.33 LHSV,with two types of catalyst charges:

(A) 2 vol. of a platinum alumina reforming catalyst upstream 1 vol. of4.6% Ni-olfretite downstream,

(B) 2 vol. of a platinum-alumina reforming catalyst upstream 1 vol. ofPt-CaA zeolite downstream.

The product yields and product octane numbers are compared below. Ineach case there was a significant improvement in ON.

Example 18 Example 19 Ni-Ofiretite Pt-CaA 101. 3 100. 5 56. 7 57.6 101.8 102. 0 08+ Vol percent yield 51. 5 47. 9

Example 20 A C reformate efiiuent stream similar in composition to thatgiven in Examples 9-10, simulating a naphtha intermediate obtained fromcontacting a naphtha feed with a platinum reforming catalyst, iscontacted with a pelleted catalyst consisting of a mechanical mixture ofNi-oifretite catalyst (as in Examples 9-10) and an amorphoussilica-alumina cracking catalyst, at conditions as in Examples 9-10.While in Examples 9-10 the concentration of aromatics in the productincreased to a level of 60 to 63% the aromatics concentration in thepresently described example is found to increase to a value in excess of70%. At the same time the concentrations of both n-parafiin andiso-paraffin are found to be markedly reduced.

As further examples of the improved method and process of thisinvention, the following tables of data are presented which providecomparative data of results obtained when upgrading different naphthafeeds by 1) a conventional prior art three-reactor reforming method, (2)a combined operation of the method of this invention wherein theselective conversion catalyst is retained along with platinum reformingcatalyst in the third reactor of a three reactor reforming process and(3) an operation similar to (2) above except that the selectiveconversion catalyst is retained in a separate fourth reactor downstreamof the third reforming reactor. Table I below presents a comparativeproduct distribution obtained when processing a C 350 F. Aramco naphthaat 500 p.s.i.g. under conditions to produce both 102 and 104 C +(R+3) ONproduct.

TABLE L-COMPARISON, PRODUCT DISTRIBUTION, PROCESSING C 350 I ArarncoNaphtha, 500 P.s.i.g.

102 104 C5+R+3 ON Comb. Sep Conv Comb. Sepfi Total C -C 15.8 19. 9 17. 119.8 22. 8 19.6

Hz, SCFB 450 280 310 450 310 340 Reformer H2 Purity, Mol percent- 69 6178 62 58 73 Estimated.

Table II below presents a comparative product distribution obtained Whenprocessing a C,,--380 F. Mid C ontinent naphtha at 500 p.s.i.g. underconditions to produce both 102 and 104 C +(R+3) ON product.

carbons over that obtained by conventional reforming operations. *InTable I, substantially higher yields of C product were obtained whenprocessing to 104 ON prodnot by the combination and separate processingroutes TABLE II.-COMPARISON PRODUCT DISTRIBUTION PROCESSING Co380 F. MidContinent, 500 P.s.l.g., No Driers 102 104 a-i- (R+3) 0N Conv. Comb.Sep. Conv. Comb. Sep.

Ca+ V01. percent. 67. 1 68. 6 68. 6 59. 8 64. 3 62. 8 05+, Vol.percent-. 75. 9 72.3 74.0 71.2 68.8 70. 0

1 C V01. percent. 5. 8 3. 2 3.6 7. 4 4. 1 4. 7 11 C Vol. percent 3. 00.5 1. 8 4. 0 0. 4 2. 5

Total Ci, Vol. percent 8. 8 3. 7 5. 4 11.4 4. 5 7. 2

1 C4, V01. percent 3. 8 2.1 3. 9 4. 6 3.3 4. 9 n C4, Vol. percent 5. 42. 0 3. 4 6. 5 1. 6 4. 8

Total 04, Vol. percent. 9.2 4. 1 7. 3 11.1 4. 9 9. 5

05, Wt. percent 6.1 9. 9 10.6 7.1 10. 4 11. 5 0 Wt. percent 3. 5 4. 9 2.4 4. 7 6. 1 3. 2 C Wt. percent 1. 9 3. 8 1.6 2.8 4.8 1.7

Total C -C3, Wt. percent..- 11. 5 18.6 14. 6 14.6 21.3 16. 4

Hz, SOFB 780 520 630 780 550 680 Reformer H2 Purity, M01 percent. 79 6683 74 64 80 Estimated.

Table III below presents a comparison of product distribution obtainedby conventional and combined reforming as described above whenprocessing an N C -36O F. Mid-Continent naphtha at 500 p.s.1.g. toproduce 102 C R+3) ON product.

TABLE III.COMPARISON PRODUCT DISTRIBUTION PROCESSING N C4360 F. MC, 500P.s.i.g.

102 C R 3 ON 5+ Conv. Comb.

Total C1-C2 14. 9 20. 0

H3 SCFB 480 440 Reformer H2 Purity, Moi Percent 66 64 It is demonstratedby the data presented in the above tables that the yields of 0 productwere higher for the combined and separate processing methods over thatobtainable by a conventional reforming operation. The data further showselective conversion of n-paraffins in the process by virtue of thehigher yields of C hydroover that obtained by conventional reforming. Itshould also be noted that significant improvement in yields of C wasalso obtained. Table III on the other hand, shows that the combinationprocessing method of this invention realized significant improvementsfor both C and C products over conventional reforming. Furthermore, thecombination processing route also produced higher yields of Chydrocarbons than obtained by conventional reforming.

Having thus generally described the improved methods of this inventionand provided examples directed thereto, reference is now had to thedrawing (FIGURE 2) which provides one arrangement of contacting stepsfor practicing the invention described.

Referring now to FIGURE 2 by way of example, a process flow arrangementis diagrammatically shown comprising a three reactor (R R and Rreforming system, a reformate product separator, a depropanizer towerand a debutanizer tower from which a C reformate product can berecovered. The naphtha boiling range hydrocarbon feed enters the processby conduit 2, is combined with a hydrogen rich recycle gas in conduit 4and passed by conduit 6 to reforming reactor R The naphtha feed may bebrought up to reforming temperatures in a suitable heater now showneither before or after admixture with the hydrogen rich recycle gas, sothat it has an inlet temperature sufficiently high to provide theendothermic reaction heat required in R The combined stream of hydrogenand hydrocarbon flows in series through r17 R conduit 8, heater 10,conduit 12, reactor R conduit 14, heater 16, conduit 18 to reactor R Inthis arrangement R houses a portion of a platinum type reformingcatalyst in upstream portion of the reactor and the selective type Bcatalyst described above in the downstream portion of the reactor.

In reactor R the total reformate product moves in contact with theselective upgrading catalyst under conditions to obtain the selectiveconversion of hydrocarbons described above. The total product efiluentof reactor R is thereafter passed to a suitable separator vessel 24 byconduit 20 containing heat exchanger 22. In separator 24, a hydrogenrich recycle gas stream is separated from the remaining reformateproduct and removed by conduit 26 for recycle to conduit 4. A portion ofthis recycle gas may be withdrawn by conduit 28. The remaining reformateproduct is removed by separator 24 by conduit 30, passed through heatexchanger 22 and then through conduit 34 to a depropanizer tower 36. Intower 36, C and lighter hydrocarbons are separated and removed byconduit 38 from the reformate product. The depropanized effluent is thenpassed by conduit 40 to a debutanized tower 42. Butane rich gas isrecovered from tower 42 by conduit 44 and a reformate rich in aromaticsand branch chained hydrocarbons is recovered by conduit 46. The sensibleheat of the product stream of R may be utilized to preheat the freshnaphtha feeds passed to the process by heat exchange in heat exchange22.

The reactions involving the selective upgrading catalyst portion of theprocess result in a liberation of heat; it is contemplated therefore,that interspacing of selective type B catalyst with the reforming typecatalyst in any reactor in the series of reactors can be practiced in amanner to take advantage of this heat liberation. Accordingly, someportions of catalyst type B charge can be included in reactors precedingreactor R This will be particularly advantageous when the objective ofthe process is the production of aromatics concentrates.

The charge stock selected for passage through the selectoformingprocess, in any of its varied embodiments described may be especiallyselected in composition or in boiling range so as to obtain maximumbenefits from the process. For example, it has been pointed out that theadvantages in product yield of the new upgrading process and method aregreatest for a paraffinic as compared to a highly naphthenic chargestock. If various naphth'as are to be reformed it will be advantageousto process at least portions of the more naphthenic stocks only overreforming catalyst reactors while passing the more paraffinic chargestock through a selectoforming train of catalysts.

It is contemplated, for example, to process naphthenic charge stocksonly over type A catalyst contained in portions of the processingsystem, and more paraffinic charge stocks through the entire sequence ofcatalyst in the reactor system in, for example, a blocked out operation.

Also processing in the selectoforming reactor system of this inventionmay be advantageously confined to the naphtha portion boilingsubstantially above about C hydrocarbon since n-pentane is well known tohave an adequately high octane number and therefore curbing a need forfurther conversion or elimination from the product. Also, a C toapproximately C cut of naphtha may be selected as feed for preferentialtreatment by the selective process. For example, after contact with typeA catalyst the intermediate product may be split into an approximate 0and a C3- portion; the C or the higher boiling portion removed from thetrain while the C or lower boiling portion is allowed to proceed tocontact type B catalyst. Alternately, we may provide a separation of theselectoforming product stream into desired portions of specific boilingrange, and recycle one or more portions of the separated reactionproducts to a bed of catalyst or reactor containing at least a majorityportion of type B catalyst. Clearly, selection of product streams forrecycle of the cuts of highest paraffin content, or the cuts having thelowest octane number due to the presence of n-hydrocarbons will be mostadvantageous.

Having thus provided a general description of the invention andpresented several examples in support thereof, it is to be understoodthat no undue restrictions are to be imposed by reason thereof.

I claim:

1. A method for increasing the octane number of a naphtha hydrocarbonfraction which comprises:

(a) reforming a naphtha hydrocarbon fraction in the presence of aplatinum group reforming catalyst to an octane number not substantiallyabove about 0N.

(b) passing the reformate of said platinum reforming step with hydrogenin contact with a shape-selective crystalline aluminosilicatehydrocracking catalyst having a silica to alumina ratio to at leastabout 3.0 and a pore size of about 4.5 to 6 Angstrom units, saidshape-selective crystalline aluminosilicate catalyst having cracking andhydrogenation/dehydrogenation activity limited to substantially withinits internal pore structure so as to permit selective conversion of thenormal parafiins in said reformate to saturated lower boiling products;and

(c) recovering a naphtha fraction from said selective conversion stephave an 0N. above about [100.

2. The method of claim 1 wherein the platinum type reforming catalystsis predominantly an eta alumina'based catalyst and reforming of thenaphtha is effected under substantially desiccated reforming conditionsat a pressure below about 500 p.s.i.g.

3. The method of claim 1 wherein the selective hydrogenating catalystcomprises a highly porous material in which the hydrogenating componentmay be made to exist in either a monoatomic form or an agregation formdepending upon the composition of the gasiform material desired.

4. The method of claim 1 wherein the n-paraffin selective conversionstep is effected in the presence of a physical mixture of the platinumtype reforming catalyst and the selective hydrogenating catalyst.

5. The method of claim 1 wherein the selective catalyst is maintained ina separate reactor downstream of the reactors containing platinum typereforming catalyst.

6. In a process for reforming naphtha hydrocarbons employing a pluralityof fixed catalyst bed reaction zones through which the naphthahydrocarbon is passed sequentially in contact with a platinum groupmetal reforming catalyst under reforming conditions of pressure selectedfrom within the range of from about 100 to about 600 p.s.i.g., atemperature selected from within the range of from about 800 F. to about1000 F., and a liquid hourly space velocity selected from within therange of from about 0.5 to about 5, the method of improving the productoctane quality-liquid yield ratio of the liquid reformate productwithout increasing the severity of the reforming operation beyond about100 octane number product which comprises replacing a part of theplatinum group reforming catalyst downstream of the reforming catalystin at least the last fixed catalyst bed with a shape-selectivecrystalline aluminosilicate hydrocracking catalyst having asilica-alumina ratio of at least about 3.0 and a pore size limitedwithin the range of from 4.5 to 6 Angstroms, said shape-selectivecrystalline aluminosilicate catalyst having cracking andhydrogenation-dehydrogenation activity limited to substantially withinthe pores of the shapeselective catalysts by virtue of the method ofpreparing the catalyst and recovering a liquid product from contactingsaid shape-selective catalyst having an octane number substantiallyabove that of the 100 octane number liquid reformate product obtained bycontact with the platinum group metal reforming catalyst.

7. In a method for processing a hydrocarbon fraction boiling in thenaphtha range by mixing said hydrocarbon fraction with hydrogen,contacting the mixture at a pressure below 600 p.s.i.g. and atemperature in the range of 800 F, to 1000 F. with a multiple functionreforming catalyst having activity for hydrocyclization, isomerizationand hydrogenation-dehydrogen.ation reactions which reforming catalyst iselfective for conversion of molecules in the charge regardless of siZeor configuration and contacting with a shape-selective conversioncatalyst, a hydrocarbon charge of the class consisting of saidhydrocarbon fraction and products obtained from contacting saidhydrocarbon fraction with said reforming catalyst, the improvement whichcomprises employing a shapeselective crystalline aluminosilicateconversion catalyst characterized by having pores of .a size selectedfrom within the range of 4 to 6 Angstroms having multiple functions ofcracking and hydrogenation-dehydrogenation activity by reason of baseexchange with one or more solutions containing ions of the classconsisting of hydrogen ions and ammonium ions and by the presence of ahydrogenation-debydrogenation transition metal within the pores thereofwhich pores admit substantially only normal hydrocarbons and excludehydrocarbons of other configurations and conducting a separation stepwith respect to the mixture of hydrogen with products resulting fromreaction with both said reforming and said shapeselective multiplefunction catalyst.

8. The method of claim 1 wherein the selective conversion step iseffected at the same pressure as the reforming step.

9. The method of claim 1 wherein the selective conversion step iseffected at a higher pressure than the reforming step.

10. The selectoforming process for upgrading naphtha which comprisescontacting a charge naphtha in the presence of hydrogen with a reformingcatalyst effective for converting hydrocarbon components of the naphthato other hydrocarbons of a higher octane number than charge componentsby reactions which include dehydrogenation of naphthenes to yieldaromatics and hydrogen, thereafter passing hydrocarbon products of saidreforming step consisting essentially of a mixture of aromatic andparafiinic components in admixture with hydrogen in contact with ashape-selective crystalline aluminosilicate hydrocracking catalysthaving a silica to alumina ratio of at least 3.0 and a pore size ofabout 4.5 to 6 Angstrom units, said shape-selective crystallinealuminosilicate having cracking and hydrogenation/dehydrogenationactivity substantially limited to its internal pore structure Whereby afurther increase in octane number of the charged naphtha is obtained byselectively hydro-cracking normal parafiins to compounds boiling belownaphtha hydrocarbon at lower cost in yield than that achievable at thefinal octane number by more severe reforming.

11. The selectoforming process for upgrading naphtha of less than ninetyresearch octane number to thereby produce a fraction suitable as a motorgasoline component and having a target research octane number greaterthan 100, which process comprises contacting the charge naphtha with areforming catalyst under reforming conditions at a severity suflicientto raise the research octane number of the reformate product to a levelnot less than about two octane numbers below the target value andthereafter subjecting the resultant reformate to shape selectivehydrocracking with a crystalline aluminos-ilicate hydrocracking catalysthaving a silica to alumina ratio of at least 3.0, a pore size of about4.5 to 6 Angstrom units and having cracking andhydrogenation/dehydrogenation activity limited to substantially withinits internal pores whereby the final octane number is raised to targetvalue through hydrocracking of normal paraflins in the effluent of thereforming step.

References Cited UNITED STATES PATENTS 3,039,953 6/1962; Eng 208-263,114,696 12/1963 WeisZ 20866 3,304,254 2/1967 Eastwood et al 208-l1l'DELBERT E. GANTZ, Primary Examiner. ABRAHAM RIMENS, Assistant Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No 3 ,395,094 July 30 1968 Paul B. Weisz It is certified that error appears inthe above id hat said Letters Patent are hereby corrected as ent ifiedpatent and t shown below:

Column 3 line 47, "B" should read A Column 8, line 57., "N-chabazlteshould read Ni-chabazite Column 10,

line 43, "B should read B Column 15, TABLE III, first column, line 7thereof, "N 3 should read N C same third column, line 12 thereof, "7.7"should read 7.0

Signed and sealed this 30th day of December l969.

(SEAL) Attest:

WILLIAM E. SCHUYLER, JR.

Edward M. Fletcher, Jr.

Commissioner of Patents Attesting Officer

